Spotlight Indexing Eating Disk or CPU on a Mac? How to Fix It
Spotlight rebuilds its search index — the mds and mds_stores processes — after macOS updates, large file changes or migrations, spiking CPU and disk until it finishes. It usually completes on its own within an hour or two. If it's stuck, rebuild the index by adding then removing your drive in Spotlight's Privacy settings, or with mdutil. The index itself is counted under System Data.
Why Spotlight spikes
Those mds and mds_stores processes hammering your CPU and disk are Spotlight re-indexing your files so search stays instant. It's triggered by macOS updates, big file operations, or restoring from a backup — and it's temporary. First step: let it finish, ideally plugged in.
Force a rebuild if it's stuck
- Via Settings: System Settings → Spotlight → Search Privacy → add your drive, then remove it. This forces a fresh index.
- Via Terminal:
sudo mdutil -E /erases and rebuilds the index for the drive. - Check status:
mdutil -s /
Where the index lives
The Spotlight index sits in your drive's hidden .Spotlight-V100 and is counted under System Data. It's not something to delete for space — it rebuilds. If System Data looks huge, the real reclaimable wins are caches and developer junk; MacCleaner shows which is which.
Frequently asked questions
Why is mds_stores using so much CPU on my Mac?
It's Spotlight re-indexing your files, usually after a macOS update or big file change. It's temporary — let it finish, ideally on power. If it runs for many hours, rebuild the index.
How do I rebuild the Spotlight index?
Add then remove your drive in System Settings → Spotlight → Search Privacy, or run sudo mdutil -E / in Terminal. Both force a clean rebuild.
Is it safe to delete the Spotlight index?
You don't need to — rebuilding recreates it. Deleting it only forces a re-index, which spikes CPU and disk again. It's not a way to free lasting space.
Reclaim the space in two taps
MacCleaner scans read-only, shows every file before anything is touched, marks the safe groups, and lets you choose Trash or permanent. Free for up to 500 MB of cleanup a day.
Download for Mac